/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 
package com.nebula.base.utils;

import java.io.File;
import java.io.IOException;
import java.lang.annotation.Annotation;
import java.lang.reflect.AccessibleObject;
import java.lang.reflect.Array;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.GenericArrayType;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Member;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;
import java.lang.reflect.WildcardType;
import java.net.URL;
import java.net.URLDecoder;
import java.nio.charset.StandardCharsets;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.jar.JarFile;

/**
 * @author : wh
 * @date : 2023/11/18 14:06
 * @description:
 */
public class ClassUtil {
    
    /**
     * Empty class array.
     */
    public static final Class[] EMPTY_CLASS_ARRAY = new Class[0];
    
    @SuppressWarnings("unchecked")
    public static <T> Class<T>[] emptyClassArray() {
        return EMPTY_CLASS_ARRAY;
    }
    
    public static final String METHOD_GET_PREFIX = "get";
    public static final String METHOD_IS_PREFIX = "is";
    public static final String METHOD_SET_PREFIX = "set";
    
    // ---------------------------------------------------------------- find method
    
    /**
     * Returns method from an object, matched by name. This may be considered as
     * a slow operation, since methods are matched one by one.
     * Returns only accessible methods.
     * Only first method is matched.
     *
     * @param c          class to examine
     * @param methodName Full name of the method.
     * @return null if method not found
     */
    public static Method findMethod(final Class c, final String methodName) {
        return findDeclaredMethod(c, methodName, true);
    }
    
    /**
     * @see #findMethod(Class, String)
     */
    public static Method findDeclaredMethod(final Class c, final String methodName) {
        return findDeclaredMethod(c, methodName, false);
    }
    
    private static Method findDeclaredMethod(final Class c, final String methodName, final boolean publicOnly) {
        if ((methodName == null) || (c == null)) {
            return null;
        }
        final Method[] ms = publicOnly ? c.getMethods() : c.getDeclaredMethods();
        for (final Method m : ms) {
            if (m.getName().equals(methodName)) {
                return m;
            }
        }
        return null;
    }
    
    // ---------------------------------------------------------------- find ctor
    
    /**
     * Finds constructor with given parameter types. First matched ctor is returned.
     */
    public static <T> Constructor<T> findConstructor(final Class<T> clazz, final Class<?>... parameterTypes) {
        final Constructor<?>[] constructors = clazz.getConstructors();
        
        Class<?>[] pts;
        
        for (final Constructor<?> constructor : constructors) {
            pts = constructor.getParameterTypes();
            
            if (isAllAssignableFrom(pts, parameterTypes)) {
                return (Constructor<T>) constructor;
            }
        }
        return null;
    }
    
    /**
     * Returns {@code true} if all types are assignable from the other array of types.
     */
    public static boolean isAllAssignableFrom(final Class<?>[] typesTarget, final Class<?>[] typesFrom) {
        if (typesTarget.length == typesFrom.length) {
            for (int i = 0; i < typesTarget.length; i++) {
                if (!typesTarget[i].isAssignableFrom(typesFrom[i])) {
                    return false;
                }
            }
            return true;
        }
        return false;
    }
    
    // ---------------------------------------------------------------- classes
    
    /**
     * Returns classes from array of objects. It accepts {@code null}
     * values.
     */
    public static Class[] getClasses(final Object... objects) {
        if (objects.length == 0) {
            return EMPTY_CLASS_ARRAY;
        }
        final Class[] result = new Class[objects.length];
        for (int i = 0; i < objects.length; i++) {
            if (objects[i] != null) {
                result[i] = objects[i].getClass();
            }
        }
        return result;
    }
    
    // ---------------------------------------------------------------- match classes
    
    /**
     * Safe version of <code>isAssignableFrom</code> method that
     * returns <code>false</code> if one of the arguments is <code>null</code>.
     */
    public static boolean isTypeOf(final Class<?> lookupClass, final Class<?> targetClass) {
        if (targetClass == null || lookupClass == null) {
            return false;
        }
        return targetClass.isAssignableFrom(lookupClass);
    }
    
    /**
     * Safe version of <code>isInstance</code>, returns <code>false</code>
     * if any of the arguments is <code>null</code>.
     */
    public static boolean isInstanceOf(final Object object, final Class target) {
        if (object == null || target == null) {
            return false;
        }
        return target.isInstance(object);
    }
    
    /**
     * Resolves all interfaces of a type. No duplicates are returned.
     * Direct interfaces are prior the interfaces of subclasses in
     * the returned array.
     */
    public static Class[] resolveAllInterfaces(final Class type) {
        final Set<Class> bag = new LinkedHashSet<>();
        _resolveAllInterfaces(type, bag);
        
        return bag.toArray(new Class[0]);
    }
    
    private static void _resolveAllInterfaces(final Class type, final Set<Class> bag) {
        // add types interfaces
        final Class[] interfaces = type.getInterfaces();
        Collections.addAll(bag, interfaces);
        
        // resolve interfaces of each interface
        for (final Class iface : interfaces) {
            _resolveAllInterfaces(iface, bag);
        }
        
        // continue with super type
        final Class superClass = type.getSuperclass();
        
        if (superClass == null) {
            return;
        }
        
        if (superClass == Object.class) {
            return;
        }
        
        _resolveAllInterfaces(type.getSuperclass(), bag);
    }
    
    /**
     * Resolves all super classes, from top (direct subclass) to down. <code>Object</code>
     * class is not included in the list.
     */
    public static Class[] resolveAllSuperclasses(Class type) {
        final List<Class> list = new ArrayList<>();
        
        while (true) {
            type = type.getSuperclass();
            
            if ((type == null) || (type == Object.class)) {
                break;
            }
            list.add(type);
        }
        
        return list.toArray(new Class[0]);
    }
    
    // ---------------------------------------------------------------- accessible methods
    
    /**
     * Returns array of all methods that are accessible from given class.
     *
     * @see #getAccessibleMethods(Class, Class)
     */
    public static Method[] getAccessibleMethods(final Class clazz) {
        return getAccessibleMethods(clazz, Object.class);
    }
    
    /**
     * Returns array of all methods that are accessible from given class, upto limit
     * (usually <code>Object.class</code>). Abstract methods are ignored.
     */
    public static Method[] getAccessibleMethods(Class clazz, final Class limit) {
        final Package topPackage = clazz.getPackage();
        final List<Method> methodList = new ArrayList<>();
        final int topPackageHash = topPackage == null ? 0 : topPackage.hashCode();
        boolean top = true;
        do {
            if (clazz == null) {
                break;
            }
            final Method[] declaredMethods = clazz.getDeclaredMethods();
            for (final Method method : declaredMethods) {
                if (Modifier.isVolatile(method.getModifiers())) {
                    continue;
                }
                // if (Modifier.isAbstract(method.getModifiers())) {
                // continue;
                // }
                if (top) { // add all top declared methods
                    methodList.add(method);
                    continue;
                }
                final int modifier = method.getModifiers();
                if (Modifier.isPrivate(modifier)) {
                    continue; // ignore super private methods
                }
                if (Modifier.isAbstract(modifier)) { // ignore super abstract methods
                    continue;
                }
                if (Modifier.isPublic(modifier)) {
                    addMethodIfNotExist(methodList, method); // add super public methods
                    continue;
                }
                if (Modifier.isProtected(modifier)) {
                    addMethodIfNotExist(methodList, method); // add super protected methods
                    continue;
                }
                // add super default methods from the same package
                final Package pckg = method.getDeclaringClass().getPackage();
                final int pckgHash = pckg == null ? 0 : pckg.hashCode();
                if (pckgHash == topPackageHash) {
                    addMethodIfNotExist(methodList, method);
                }
            }
            top = false;
        } while ((clazz = clazz.getSuperclass()) != limit);
        
        final Method[] methods = new Method[methodList.size()];
        for (int i = 0; i < methods.length; i++) {
            methods[i] = methodList.get(i);
        }
        return methods;
    }
    
    private static void addMethodIfNotExist(final List<Method> allMethods, final Method newMethod) {
        for (final Method m : allMethods) {
            if (compareSignatures(m, newMethod)) {
                return;
            }
        }
        allMethods.add(newMethod);
    }
    
    // ---------------------------------------------------------------- accessible fields
    
    public static Field[] getAccessibleFields(final Class clazz) {
        return getAccessibleFields(clazz, Object.class);
    }
    
    public static Field[] getAccessibleFields(Class clazz, final Class limit) {
        final Package topPackage = clazz.getPackage();
        final List<Field> fieldList = new ArrayList<>();
        final int topPackageHash = topPackage == null ? 0 : topPackage.hashCode();
        boolean top = true;
        do {
            if (clazz == null) {
                break;
            }
            final Field[] declaredFields = clazz.getDeclaredFields();
            for (final Field field : declaredFields) {
                if (top) { // add all top declared fields
                    fieldList.add(field);
                    continue;
                }
                final int modifier = field.getModifiers();
                if (Modifier.isPrivate(modifier)) {
                    continue; // ignore super private fields
                }
                if (Modifier.isPublic(modifier)) {
                    addFieldIfNotExist(fieldList, field); // add super public methods
                    continue;
                }
                if (Modifier.isProtected(modifier)) {
                    addFieldIfNotExist(fieldList, field); // add super protected methods
                    continue;
                }
                // add super default methods from the same package
                final Package pckg = field.getDeclaringClass().getPackage();
                final int pckgHash = pckg == null ? 0 : pckg.hashCode();
                if (pckgHash == topPackageHash) {
                    addFieldIfNotExist(fieldList, field);
                }
            }
            top = false;
        } while ((clazz = clazz.getSuperclass()) != limit);
        
        final Field[] fields = new Field[fieldList.size()];
        for (int i = 0; i < fields.length; i++) {
            fields[i] = fieldList.get(i);
        }
        return fields;
    }
    
    private static void addFieldIfNotExist(final List<Field> allFields, final Field newField) {
        for (final Field f : allFields) {
            if (compareSignatures(f, newField)) {
                return;
            }
        }
        allFields.add(newField);
    }
    
    // ---------------------------------------------------------------- supported methods
    
    public static Method[] getSupportedMethods(final Class clazz) {
        return getSupportedMethods(clazz, Object.class);
    }
    
    /**
     * Returns a <code>Method</code> array of the methods to which instances of the specified
     * respond except for those methods defined in the class specified by limit
     * or any of its superclasses. Note that limit is usually used to eliminate
     * them methods defined by <code>java.lang.Object</code>. If limit is <code>null</code> then all
     * methods are returned.
     */
    public static Method[] getSupportedMethods(final Class clazz, final Class limit) {
        final ArrayList<Method> supportedMethods = new ArrayList<>();
        for (Class c = clazz; c != limit && c != null; c = c.getSuperclass()) {
            final Method[] methods = c.getDeclaredMethods();
            for (final Method method : methods) {
                boolean found = false;
                for (final Method supportedMethod : supportedMethods) {
                    if (compareSignatures(method, supportedMethod)) {
                        found = true;
                        break;
                    }
                }
                if (!found) {
                    supportedMethods.add(method);
                }
            }
        }
        return supportedMethods.toArray(new Method[0]);
    }
    
    public static Field[] getSupportedFields(final Class clazz) {
        return getSupportedFields(clazz, Object.class);
    }
    
    public static Field[] getSupportedFields(final Class clazz, final Class limit) {
        final ArrayList<Field> supportedFields = new ArrayList<>();
        for (Class c = clazz; c != limit && c != null; c = c.getSuperclass()) {
            final Field[] fields = c.getDeclaredFields();
            for (final Field field : fields) {
                boolean found = false;
                for (final Field supportedField : supportedFields) {
                    if (compareSignatures(field, supportedField)) {
                        found = true;
                        break;
                    }
                }
                if (!found) {
                    supportedFields.add(field);
                }
            }
        }
        return supportedFields.toArray(new Field[0]);
    }
    
    // ---------------------------------------------------------------- compare
    
    /**
     * Compares method declarations: signature and return types.
     */
    public static boolean compareDeclarations(final Method first, final Method second) {
        if (first.getReturnType() != second.getReturnType()) {
            return false;
        }
        return compareSignatures(first, second);
    }
    
    /**
     * Compares method signatures: names and parameters.
     */
    public static boolean compareSignatures(final Method first, final Method second) {
        if (!first.getName().equals(second.getName())) {
            return false;
        }
        return compareParameters(first.getParameterTypes(), second.getParameterTypes());
    }
    
    /**
     * Compares constructor signatures: names and parameters.
     */
    public static boolean compareSignatures(final Constructor first, final Constructor second) {
        if (!first.getName().equals(second.getName())) {
            return false;
        }
        return compareParameters(first.getParameterTypes(), second.getParameterTypes());
    }
    
    public static boolean compareSignatures(final Field first, final Field second) {
        return first.getName().equals(second.getName());
    }
    
    /**
     * Compares classes, usually method or ctor parameters.
     */
    public static boolean compareParameters(final Class[] first, final Class[] second) {
        if (first.length != second.length) {
            return false;
        }
        for (int i = 0; i < first.length; i++) {
            if (first[i] != second[i]) {
                return false;
            }
        }
        return true;
    }
    
    // ---------------------------------------------------------------- force
    
    /**
     * Suppress access check against a reflection object. SecurityException is silently ignored.
     * Checks first if the object is already accessible.
     */
    public static void forceAccess(final AccessibleObject accObject) {
        try {
            if (System.getSecurityManager() == null) {
                accObject.setAccessible(true);
            } else {
                AccessController.doPrivileged((PrivilegedAction) () -> {
                    accObject.setAccessible(true);
                    return null;
                });
            }
        } catch (final SecurityException sex) {
            // ignore
        }
    }
    
    // ---------------------------------------------------------------- is public
    
    /**
     * Returns <code>true</code> if class member is public.
     */
    public static boolean isPublic(final Member member) {
        return Modifier.isPublic(member.getModifiers());
    }
    
    /**
     * Returns <code>true</code> if class member is public and if its declaring class is also public.
     */
    public static boolean isPublicPublic(final Member member) {
        if (Modifier.isPublic(member.getModifiers())) {
            if (Modifier.isPublic(member.getDeclaringClass().getModifiers())) {
                return true;
            }
        }
        return false;
    }
    
    /**
     * Returns <code>true</code> if class is public.
     */
    public static boolean isPublic(final Class c) {
        return Modifier.isPublic(c.getModifiers());
    }
    
    // ---------------------------------------------------------------- create
    
    /**
     * Creates new instance of given class with given optional arguments.
     */
    @SuppressWarnings("unchecked")
    public static <T> T newInstance(final Class<T> clazz,
                                    final Object... params) throws InstantiationException, IllegalAccessException, InvocationTargetException, NoSuchMethodException {
        if (params.length == 0) {
            return newInstance(clazz);
        }
        
        final Class<?>[] paramTypes = getClasses(params);
        
        final Constructor<?> constructor = findConstructor(clazz, paramTypes);
        
        if (constructor == null) {
            throw new InstantiationException("No constructor matched parameter types.");
        }
        
        return (T) constructor.newInstance(params);
    }
    
    /**
     * Creates new instances including for common mutable classes that do not have a default constructor.
     * more user-friendly. It examines if class is a map, list,
     * String, Character, Boolean or a Number. Immutable instances are cached and not created again.
     * Arrays are also created with no elements. Note that this bunch of <code>if</code> blocks
     * is faster then using a <code>HashMap</code>.
     */
    @SuppressWarnings("unchecked")
    public static <T> T newInstance(
                                    final Class<T> type) throws IllegalAccessException, InstantiationException, NoSuchMethodException, InvocationTargetException {
        if (type.isPrimitive()) {
            if (type == int.class) {
                return (T) Integer.valueOf(0);
            }
            if (type == long.class) {
                return (T) Long.valueOf(0);
            }
            if (type == boolean.class) {
                return (T) Boolean.FALSE;
            }
            if (type == float.class) {
                return (T) Float.valueOf(0);
            }
            if (type == double.class) {
                return (T) Double.valueOf(0);
            }
            if (type == byte.class) {
                return (T) Byte.valueOf((byte) 0);
            }
            if (type == short.class) {
                return (T) Short.valueOf((short) 0);
            }
            if (type == char.class) {
                return (T) Character.valueOf((char) 0);
            }
            throw new IllegalArgumentException("Invalid primitive: " + type);
        }
        
        if (type.getName().startsWith("java.")) {
            
            if (type == Integer.class) {
                return (T) Integer.valueOf(0);
            }
            if (type == String.class) {
                return (T) StringPool.EMPTY;
            }
            if (type == Long.class) {
                return (T) Long.valueOf(0);
            }
            if (type == Boolean.class) {
                return (T) Boolean.FALSE;
            }
            if (type == Float.class) {
                return (T) Float.valueOf(0);
            }
            if (type == Double.class) {
                return (T) Double.valueOf(0);
            }
            
            if (type == Map.class) {
                return (T) new HashMap();
            }
            if (type == List.class) {
                return (T) new ArrayList();
            }
            if (type == Set.class) {
                return (T) new HashSet();
            }
            if (type == Collection.class) {
                return (T) new ArrayList();
            }
            
            if (type == Byte.class) {
                return (T) Byte.valueOf((byte) 0);
            }
            if (type == Short.class) {
                return (T) Short.valueOf((short) 0);
            }
            if (type == Character.class) {
                return (T) Character.valueOf((char) 0);
            }
        }
        
        if (type.isEnum()) {
            return type.getEnumConstants()[0];
        }
        
        if (type.isArray()) {
            return (T) Array.newInstance(type.getComponentType(), 0);
        }
        
        final Constructor<T> declaredConstructor = type.getDeclaredConstructor();
        
        forceAccess(declaredConstructor);
        
        return declaredConstructor.newInstance();
    }
    
    // ---------------------------------------------------------------- misc
    
    /**
     * Returns <code>true</code> if the first member is accessible from second one.
     */
    public static boolean isAssignableFrom(final Member member1, final Member member2) {
        return member1.getDeclaringClass().isAssignableFrom(member2.getDeclaringClass());
    }
    
    /**
     * Returns all superclasses.
     */
    public static Class[] getSuperclasses(final Class type) {
        int i = 0;
        for (Class x = type.getSuperclass(); x != null; x = x.getSuperclass()) {
            i++;
        }
        final Class[] result = new Class[i];
        i = 0;
        for (Class x = type.getSuperclass(); x != null; x = x.getSuperclass()) {
            result[i] = x;
            i++;
        }
        return result;
    }
    
    /**
     * Returns <code>true</code> if method is user defined and not defined in <code>Object</code> class.
     */
    public static boolean isUserDefinedMethod(final Method method) {
        return method.getDeclaringClass() != Object.class;
    }
    
    /**
     * Returns <code>true</code> if method defined in <code>Object</code> class.
     */
    public static boolean isObjectMethod(final Method method) {
        return method.getDeclaringClass() == Object.class;
    }
    
    /**
     * Returns <code>true</code> if method is a bean property.
     */
    public static boolean isBeanProperty(final Method method) {
        if (isObjectMethod(method)) {
            return false;
        }
        final String methodName = method.getName();
        final Class returnType = method.getReturnType();
        final Class[] paramTypes = method.getParameterTypes();
        if (methodName.startsWith(METHOD_GET_PREFIX)) { // getter method must starts with 'get' and it is not getClass()
            if ((returnType != null) && (paramTypes.length == 0)) { // getter must have a return type and no arguments
                return true;
            }
        } else if (methodName.startsWith(METHOD_IS_PREFIX)) { // ister must starts with 'is'
            if ((returnType != null) && (paramTypes.length == 0)) { // ister must have return type and no arguments
                return true;
            }
        } else if (methodName.startsWith(METHOD_SET_PREFIX)) { // setter must start with a 'set'
            if (paramTypes.length == 1) { // setter must have just one argument
                return true;
            }
        }
        return false;
    }
    
    /**
     * Returns <code>true</code> if method is bean getter.
     */
    public static boolean isBeanPropertyGetter(final Method method) {
        return getBeanPropertyGetterPrefixLength(method) != 0;
    }
    
    private static int getBeanPropertyGetterPrefixLength(final Method method) {
        if (isObjectMethod(method)) {
            return 0;
        }
        final String methodName = method.getName();
        final Class returnType = method.getReturnType();
        final Class[] paramTypes = method.getParameterTypes();
        if (methodName.startsWith(METHOD_GET_PREFIX)) { // getter method must starts with 'get' and it is not getClass()
            if ((returnType != null) && (paramTypes.length == 0)) { // getter must have a return type and no arguments
                return 3;
            }
        } else if (methodName.startsWith(METHOD_IS_PREFIX)) { // ister must starts with 'is'
            if ((returnType != null) && (paramTypes.length == 0)) { // ister must have return type and no arguments
                return 2;
            }
        }
        return 0;
    }
    
    /**
     * Returns property name from a getter method.
     * Returns <code>null</code> if method is not a real getter.
     */
    public static String getBeanPropertyGetterName(final Method method) {
        final int prefixLength = getBeanPropertyGetterPrefixLength(method);
        if (prefixLength == 0) {
            return null;
        }
        final String methodName = method.getName().substring(prefixLength);
        return StringUtils.decapitalize(methodName);
    }
    
    /**
     * Returns <code>true</code> if method is bean setter.
     */
    public static boolean isBeanPropertySetter(final Method method) {
        return getBeanPropertySetterPrefixLength(method) != 0;
    }
    
    private static int getBeanPropertySetterPrefixLength(final Method method) {
        if (isObjectMethod(method)) {
            return 0;
        }
        final String methodName = method.getName();
        final Class[] paramTypes = method.getParameterTypes();
        if (methodName.startsWith(METHOD_SET_PREFIX)) { // setter must start with a 'set'
            if (paramTypes.length == 1) { // setter must have just one argument
                return 3;
            }
        }
        return 0;
    }
    
    /**
     * Returns beans property setter name or <code>null</code> if method is not a real setter.
     */
    public static String getBeanPropertySetterName(final Method method) {
        final int prefixLength = getBeanPropertySetterPrefixLength(method);
        if (prefixLength == 0) {
            return null;
        }
        final String methodName = method.getName().substring(prefixLength);
        return StringUtils.decapitalize(methodName);
    }
    
    // ---------------------------------------------------------------- generics
    
    /**
     * Returns single component type. Index is used when type consist of many
     * components. If negative, index will be calculated from the end of the
     * returned array. Returns <code>null</code> if component type
     * does not exist or if index is out of bounds.
     *
     * @see #getComponentTypes(java.lang.reflect.Type)
     */
    public static Class getComponentType(final Type type, final int index) {
        return getComponentType(type, null, index);
    }
    
    /**
     * Returns single component type for given type and implementation.
     * Index is used when type consist of many
     * components. If negative, index will be calculated from the end of the
     * returned array.  Returns <code>null</code> if component type
     * does not exist or if index is out of bounds.
     * <p>
     *
     * @see #getComponentTypes(java.lang.reflect.Type, Class)
     */
    public static Class getComponentType(final Type type, final Class implClass, int index) {
        final Class[] componentTypes = getComponentTypes(type, implClass);
        if (componentTypes == null) {
            return null;
        }
        
        if (index < 0) {
            index += componentTypes.length;
        }
        
        if (index >= componentTypes.length) {
            return null;
        }
        
        return componentTypes[index];
    }
    
    /**
     * @see #getComponentTypes(java.lang.reflect.Type, Class)
     */
    public static Class[] getComponentTypes(final Type type) {
        return getComponentTypes(type, null);
    }
    
    /**
     * Returns all component types of the given type.
     * For example the following types all have the
     * component-type MyClass:
     * <ul>
     * <li>MyClass[]</li>
     * <li>List&lt;MyClass&gt;</li>
     * <li>Foo&lt;? extends MyClass&gt;</li>
     * <li>Bar&lt;? super MyClass&gt;</li>
     * <li>&lt;T extends MyClass&gt; T[]</li>
     * </ul>
     */
    public static Class[] getComponentTypes(final Type type, final Class implClass) {
        if (type instanceof Class) {
            final Class clazz = (Class) type;
            if (clazz.isArray()) {
                return new Class[]{clazz.getComponentType()};
            }
        } else if (type instanceof ParameterizedType) {
            final ParameterizedType pt = (ParameterizedType) type;
            
            final Type[] generics = pt.getActualTypeArguments();
            
            if (generics.length == 0) {
                return null;
            }
            
            final Class[] types = new Class[generics.length];
            
            for (int i = 0; i < generics.length; i++) {
                types[i] = getRawType(generics[i], implClass);
            }
            return types;
        } else if (type instanceof GenericArrayType) {
            final GenericArrayType gat = (GenericArrayType) type;
            
            final Class rawType = getRawType(gat.getGenericComponentType(), implClass);
            if (rawType == null) {
                return null;
            }
            
            return new Class[]{rawType};
        }
        return null;
    }
    
    /**
     * Shortcut for <code>getComponentTypes(type.getGenericSuperclass())</code>.
     *
     * @see #getComponentTypes(java.lang.reflect.Type)
     */
    public static Class[] getGenericSupertypes(final Class type) {
        return getComponentTypes(type.getGenericSuperclass());
    }
    
    /**
     * Shortcut for <code>getComponentType(type.getGenericSuperclass())</code>.
     *
     * @see #getComponentType(java.lang.reflect.Type, int)
     */
    public static Class getGenericSupertype(final Class type, final int index) {
        return getComponentType(type.getGenericSuperclass(), index);
    }
    
    /**
     * Returns raw class for given <code>type</code>. Use this method with both
     * regular and generic types.
     *
     * @param type the type to convert
     * @return the closest class representing the given <code>type</code>
     * @see #getRawType(java.lang.reflect.Type, Class)
     */
    public static Class getRawType(final Type type) {
        return getRawType(type, null);
    }
    
    /**
     * Returns raw class for given <code>type</code> when implementation class is known
     * and it makes difference.
     *
     * @see #resolveVariable(java.lang.reflect.TypeVariable, Class)
     */
    public static Class<?> getRawType(final Type type, final Class implClass) {
        if (type instanceof Class) {
            return (Class) type;
        }
        if (type instanceof ParameterizedType) {
            final ParameterizedType pType = (ParameterizedType) type;
            return getRawType(pType.getRawType(), implClass);
        }
        if (type instanceof WildcardType) {
            final WildcardType wType = (WildcardType) type;
            
            final Type[] lowerTypes = wType.getLowerBounds();
            if (lowerTypes.length > 0) {
                return getRawType(lowerTypes[0], implClass);
            }
            
            final Type[] upperTypes = wType.getUpperBounds();
            if (upperTypes.length != 0) {
                return getRawType(upperTypes[0], implClass);
            }
            
            return Object.class;
        }
        if (type instanceof GenericArrayType) {
            final Type genericComponentType = ((GenericArrayType) type).getGenericComponentType();
            final Class<?> rawType = getRawType(genericComponentType, implClass);
            // this is sort of stupid, but there seems no other way (consider don't creating new instances each time)...
            return Array.newInstance(rawType, 0).getClass();
        }
        if (type instanceof TypeVariable) {
            final TypeVariable<?> varType = (TypeVariable<?>) type;
            if (implClass != null) {
                final Type resolvedType = resolveVariable(varType, implClass);
                if (resolvedType != null) {
                    return getRawType(resolvedType, null);
                }
            }
            final Type[] boundsTypes = varType.getBounds();
            if (boundsTypes.length == 0) {
                return Object.class;
            }
            return getRawType(boundsTypes[0], implClass);
        }
        return null;
    }
    
    /**
     * Resolves <code>TypeVariable</code> with given implementation class.
     */
    public static Type resolveVariable(final TypeVariable variable, final Class implClass) {
        final Class rawType = getRawType(implClass, null);
        
        int index = ArraysUtil.indexOf(rawType.getTypeParameters(), variable);
        if (index >= 0) {
            return variable;
        }
        
        final Class[] interfaces = rawType.getInterfaces();
        final Type[] genericInterfaces = rawType.getGenericInterfaces();
        
        for (int i = 0; i <= interfaces.length; i++) {
            final Class rawInterface;
            
            if (i < interfaces.length) {
                rawInterface = interfaces[i];
            } else {
                rawInterface = rawType.getSuperclass();
                if (rawInterface == null) {
                    continue;
                }
            }
            
            final Type resolved = resolveVariable(variable, rawInterface);
            if (resolved instanceof Class || resolved instanceof ParameterizedType) {
                return resolved;
            }
            
            if (resolved instanceof TypeVariable) {
                final TypeVariable typeVariable = (TypeVariable) resolved;
                index = ArraysUtil.indexOf(rawInterface.getTypeParameters(), typeVariable);
                
                if (index < 0) {
                    throw new IllegalArgumentException("Invalid type variable:" + typeVariable);
                }
                
                final Type type = i < genericInterfaces.length ? genericInterfaces[i] : rawType.getGenericSuperclass();
                
                if (type instanceof Class) {
                    return Object.class;
                }
                
                if (type instanceof ParameterizedType) {
                    return ((ParameterizedType) type).getActualTypeArguments()[index];
                }
                
                throw new IllegalArgumentException("Unsupported type: " + type);
            }
        }
        return null;
    }
    
    /**
     * Converts <code>Type</code> to a <code>String</code>. Supports successor interfaces:
     * <ul>
     * <li><code>java.lang.Class</code> - represents usual class</li>
     * <li><code>java.lang.reflect.ParameterizedType</code> - class with generic parameter (e.g. <code>List</code>)</li>
     * <li><code>java.lang.reflect.TypeVariable</code> - generic type literal (e.g. <code>List</code>, <code>T</code> - type variable)</li>
     * <li><code>java.lang.reflect.WildcardType</code> - wildcard type (<code>List&lt;? extends Number&gt;</code>, <code>"? extends Number</code> - wildcard type)</li>
     * <li><code>java.lang.reflect.GenericArrayType</code> - type for generic array (e.g. <code>T[]</code>, <code>T</code> - array type)</li>
     * </ul>
     */
    public static String typeToString(final Type type) {
        final StringBuilder sb = new StringBuilder();
        typeToString(sb, type, new HashSet<Type>());
        return sb.toString();
    }
    
    private static void typeToString(final StringBuilder sb, final Type type, final Set<Type> visited) {
        if (type instanceof ParameterizedType) {
            final ParameterizedType parameterizedType = (ParameterizedType) type;
            final Class<?> rawType = (Class<?>) parameterizedType.getRawType();
            sb.append(rawType.getName());
            boolean first = true;
            for (final Type typeArg : parameterizedType.getActualTypeArguments()) {
                if (first) {
                    first = false;
                } else {
                    sb.append(", ");
                }
                sb.append('<');
                typeToString(sb, typeArg, visited);
                sb.append('>');
            }
        } else if (type instanceof WildcardType) {
            final WildcardType wildcardType = (WildcardType) type;
            sb.append('?');
            
            // According to JLS(http://java.sun.com/docs/books/jls/third_edition/html/typesValues.html#4.5.1):
            // - Lower and upper can't coexist: (for instance, this is not allowed: <? extends List<String> & super MyInterface>)
            // - Multiple bounds are not supported (for instance, this is not allowed: <? extends List<String> & MyInterface>)
            
            final Type bound;
            if (wildcardType.getLowerBounds().length != 0) {
                sb.append(" super ");
                bound = wildcardType.getLowerBounds()[0];
            } else {
                sb.append(" extends ");
                bound = wildcardType.getUpperBounds()[0];
            }
            typeToString(sb, bound, visited);
        } else if (type instanceof TypeVariable<?>) {
            final TypeVariable<?> typeVariable = (TypeVariable<?>) type;
            sb.append(typeVariable.getName());
            
            // prevent cycles in case: <T extends List<T>>
            
            if (!visited.contains(type)) {
                visited.add(type);
                sb.append(" extends ");
                boolean first = true;
                for (final Type bound : typeVariable.getBounds()) {
                    if (first) {
                        first = false;
                    } else {
                        sb.append(" & ");
                    }
                    typeToString(sb, bound, visited);
                }
                visited.remove(type);
            }
        } else if (type instanceof GenericArrayType) {
            final GenericArrayType genericArrayType = (GenericArrayType) type;
            typeToString(genericArrayType.getGenericComponentType());
            sb.append(genericArrayType.getGenericComponentType());
            sb.append("[]");
        } else if (type instanceof Class) {
            final Class<?> typeClass = (Class<?>) type;
            sb.append(typeClass.getName());
        } else {
            throw new IllegalArgumentException("Unsupported type: " + type);
        }
    }
    
    // ---------------------------------------------------------------- annotations
    
    /**
     * Reads annotation value. Returns <code>null</code> on error
     * (e.g. when value name not found).
     */
    public static Object readAnnotationValue(final Annotation annotation, final String name) {
        try {
            final Method method = annotation.annotationType().getDeclaredMethod(name);
            return method.invoke(annotation);
        } catch (final Exception ignore) {
            return null;
        }
    }
    
    // ---------------------------------------------------------------- caller
    
    private static class ReflectUtilSecurityManager extends SecurityManager {
        
        public Class getCallerClass(final int callStackDepth) {
            return getClassContext()[callStackDepth + 1];
        }
    }
    
    private static ReflectUtilSecurityManager SECURITY_MANAGER;
    
    static {
        try {
            SECURITY_MANAGER = new ReflectUtilSecurityManager();
        } catch (final Exception ex) {
            SECURITY_MANAGER = null;
        }
    }
    
    /**
     * Emulates <code>Reflection.getCallerClass</code> using standard API.
     * This implementation uses custom <code>SecurityManager</code>
     * and it is the fastest. Other implementations are:
     * <ul>
     * <li><code>new Throwable().getStackTrace()[callStackDepth]</code></li>
     * <li><code>Thread.currentThread().getStackTrace()[callStackDepth]</code> (the slowest)</li>
     * </ul>
     * <p>
     * In case when usage of <code>SecurityManager</code> is not allowed,
     * this method fails back to the second implementation.
     * <p>
     * Note that original <code>Reflection.getCallerClass</code> is way faster
     * then any emulation.
     */
    public static Class getCallerClass(int framesToSkip) {
        if (SECURITY_MANAGER != null) {
            return SECURITY_MANAGER.getCallerClass(framesToSkip);
        }
        
        final StackTraceElement[] stackTraceElements = new Throwable().getStackTrace();
        
        if (framesToSkip >= 2) {
            framesToSkip += 4;
        }
        
        final String className = stackTraceElements[framesToSkip].getClassName();
        
        try {
            return Thread.currentThread().getContextClassLoader().loadClass(className);
        } catch (final ClassNotFoundException cnfex) {
            throw new UnsupportedOperationException(className + " not found.");
        }
    }
    
    /**
     * Smart variant of {@link #getCallerClass(int)} that skips all relevant Jodd calls.
     * However, this one does not use the security manager.
     */
    public static Class getCallerClass() {
        String className = null;
        final StackTraceElement[] stackTraceElements = new Throwable().getStackTrace();
        
        for (final StackTraceElement stackTraceElement : stackTraceElements) {
            className = stackTraceElement.getClassName();
            final String methodName = stackTraceElement.getMethodName();
            
            if (methodName.equals("loadClass")) {
                if (className.contains(ClassLoaderStrategy.class.getSimpleName())) {
                    continue;
                }
                if (className.equals(ClassLoaderUtil.class.getName())) {
                    continue;
                }
            } else if (methodName.equals("getCallerClass")) {
                continue;
            }
            break;
        }
        
        try {
            return Thread.currentThread().getContextClassLoader().loadClass(className);
        } catch (final ClassNotFoundException cnfex) {
            throw new UnsupportedOperationException(className + " not found.");
        }
    }
    
    // ---------------------------------------------------------------- enum
    
    /**
     * Returns <code>enum</code> class or <code>null</code> if class is not an enum.
     */
    public static Class findEnum(Class target) {
        if (target.isPrimitive()) {
            return null;
        }
        while (target != Object.class) {
            if (target.isEnum()) {
                return target;
            }
            
            target = target.getSuperclass();
        }
        
        return null;
    }
    
    // ---------------------------------------------------------------- misc
    
    /**
     * Returns the class of the immediate subclass of the given parent class for
     * the given object instance; or null if such immediate subclass cannot be
     * uniquely identified for the given object instance.
     */
    public static Class<?> childClassOf(final Class<?> parentClass, final Object instance) {
        
        if (instance == null || instance == Object.class) {
            return null;
        }
        
        if (parentClass != null) {
            if (parentClass.isInterface()) {
                return null;
            }
        }
        
        Class<?> childClass = instance.getClass();
        while (true) {
            final Class<?> parent = childClass.getSuperclass();
            if (parent == parentClass) {
                return childClass;
            }
            if (parent == null) {
                return null;
            }
            childClass = parent;
        }
    }
    
    /**
     * Returns the jar file from which the given class is loaded; or null
     * if no such jar file can be located.
     */
    public static JarFile jarFileOf(final Class<?> klass) {
        final URL url = klass.getResource(
                "/" + klass.getName().replace('.', '/') + ".class");
        
        if (url == null) {
            return null;
        }
        
        final String s = url.getFile();
        final int beginIndex = s.indexOf("file:") + "file:".length();
        int endIndex = s.indexOf(".jar!");
        if (endIndex == -1) {
            return null;
        }
        
        endIndex += ".jar".length();
        String f = s.substring(beginIndex, endIndex);
        // decode URL string - it may contain encoded chars (e.g. whitespaces) which are not supported for file-instances
        f = URLDecoder.decode(f, StandardCharsets.UTF_8);
        final File file = new File(f);
        
        try {
            return file.exists() ? new JarFile(file) : null;
        } catch (final IOException e) {
            throw new IllegalStateException(e);
        }
    }
    
    // ---------------------------------------------------------------- class names
    
    /**
     * Resolves class file name from class name by replacing dot's with '/' separator
     * and adding class extension at the end. If array, component type is returned.
     */
    public static String convertClassNameToFileName(Class clazz) {
        if (clazz.isArray()) {
            clazz = clazz.getComponentType();
        }
        return convertClassNameToFileName(clazz.getName());
    }
    
    /**
     * Resolves class file name from class name by replacing dot's with '/' separator.
     */
    public static String convertClassNameToFileName(final String className) {
        return className.replace('.', '/') + ".class";
    }
    
    /**
     * Returns short class name: packages are replaces with single letter.
     */
    public static String getShortClassName(final Class clazz) {
        return getShortClassName(clazz, 1);
    }
    
    public static String getShortClassName(final Class clazz, final int shortUpTo) {
        final String[] chunks = StringUtils.splitc(clazz.getName(), '.');
        final StringBuilder stringBand = new StringBuilder();
        int ndx = chunks.length - shortUpTo;
        if (ndx < 0) {
            ndx = 0;
        }
        
        for (int i = 0; i < ndx; i++) {
            if (i > 0) {
                stringBand.append('.');
            }
            stringBand.append(chunks[i].charAt(0));
        }
        
        for (int i = ndx; i < chunks.length; i++) {
            if (i > 0) {
                stringBand.append('.');
            }
            stringBand.append(chunks[i]);
        }
        return stringBand.toString();
    }
    
    // ---------------------------------------------------------------- kotlin
    
    /**
     * Returns {@code true} if type is a Kotlin class.
     */
    public static boolean isKotlinClass(final Class type) {
        final Annotation[] annotations = type.getAnnotations();
        for (final Annotation annotation : annotations) {
            if (annotation.annotationType().getName().equals("kotlin.Metadata")) {
                return true;
            }
        }
        return false;
    }
    
}
